RFR (XS): 8157459: G1 IHOP JFR event attribute with incorrect content type

[Thomas Schatzl]

Hi all,

  can I have reviews for this small fix that changes the content type
of two fields of the IHOP JFR events from bytes to percentages as they
should be?

CR:
https://bugs.openjdk.java.net/browse/JDK-8157459

(Note that the correct content type is the used PERCENTAGE, not PERCENT
as the comments in the CR indicate. There is no PERCENT).

Webrev:
http://cr.openjdk.java.net/~tschatzl/8157459/webrev/

Testing:
jprt (still running, but there is no test that checks JFR event
fields), manual testing within JMC from b124 which now correctly shows
percentages in the respective columns.

Thanks,
  Thomas